1. Field of the Invention
This invention relates to a composition comprising a synthetic resin and a silane having especially good shelf life which can be employed for the production of foundry molds. More particular, this invention relates to a composition comprising the thermosetting resin and a silane alkylated on the nitrogen and/or the silicon atom, the aminoalkylsilane being employed as an improved adhesivizing agent for an inorganic oxidic material.
2. Discussion of the Prior Art
It is known that aminoalkyl trialkoxysilanes, such as .gamma.-aminopropyltrimethoxysilane, improves the adherence of thermosetting resins to inorganic oxide material. It is furthermore known that these aminosilanes can be mixed with thermosetting phenolic resins and then these resins can be mixed directly with sands or other inorganic oxide material to be shaped and solidified (cf. DE-AS No. 1,252,853 and DE-PS No. 1,494,381).
The use of N-(aminoalkyl)-aminoalkylsilanes as adhesion improvers between thermosetting resins and inorganic oxide material is also known. These compounds are used in the same manner as the aminosilanes in which there is no substitution on the nitrogen atom (cf. U.S. Pat. No. 3,234,159).
Both the aminoalkylsilanes which are not substituted on the nitrogen atom and those which are substituted by amino groups, which are referred to hereinafter as aminosilanes, improve the adhesion of thermosetting phenolic resins to inorganic oxide substances to virtually the same degree when they are mixed with the resins. This improvement of adhesion, however, diminishes in the course of time if these aminosilane-containing resins are stored for a relatively long time at room temperature. After standing for only 14 days, the adhesion-improving action of aminosilanes declines by about 40%, and at the end of only a month the adhesivizing effect produced by .gamma.-aminopropyltriethoxysilane in phenolic resin has been reduced by one half.
The loss of the adhesivizing action of the aminosilanes in the mixture with thermosetting resins is probably due to a decomposition of these silanes in the resins. The problem therefore existed of finding an adhesivizing agent which, when mixed with thermosets, decomposes very slightly or not at all, and produces their adhesivizing action to the same or an only slightly lesser extent, even after the resin has been stored for a relatively long time, and which therefore will serve for the preparation of binding agents for inorganic oxide materials such as, for example, foundry sands, such binding agents being made from aminosilanated phenolic resins whose effectiveness will remain unaltered or only slightly reduced, even after a relatively long period of storage.